layer.conf: meta-arm-toolchain should depend on core layer

While core layer may be implied, it's still nice to depend on it explicitly
for building gcc and other toolchain components in this layer.

Signed-off-by: Denys Dmytriyenko <denys@ti.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm-toolchain/conf/layer.conf

@@ -8,6 +8,7 @@ BBFILE_COLLECTIONS += "arm-toolchain"
 BBFILE_PATTERN_arm-toolchain := "^${LAYERDIR}/"
 BBFILE_PRIORITY_arm-toolchain = "30"
 
+LAYERDEPENDS_arm-toolchain = "core"
 LAYERSERIES_COMPAT_arm-toolchain = "zeus dunfell"
 
 # do not error out on bbappends for missing recipes